WO2010143652A1

WO2010143652A1 - Method and apparatus for exposure and device fabricating method

Info

Publication number: WO2010143652A1
Application number: PCT/JP2010/059755
Authority: WO
Inventors: 徹木内
Original assignee: 株式会社ニコン
Priority date: 2009-06-10
Filing date: 2010-06-09
Publication date: 2010-12-16
Also published as: JPWO2010143652A1

Abstract

In exposing an object, an influence of temperature variations in an atmosphere, or the like is reduced, and the position of a carrier for moving the object and the surface position of the object are highly accurately measured. An exposure system for exposing a pattern onto a wafer (W1) on a wafer stage (WSA) through a projection system (PL) includes a frame (24) stationarily supported with respect to the projection system (PL) and fixed with scale plates (26B, 26C), detecting heads (28A, 30A) disposed on the wafer stage (WSA) for detecting the scaling positions of the scale plates (26B, 26C), and an autofocus system unit (36) according to a grazing incidence method for measuring the surface position of the wafer (W1) relative to a reference plane (34) formed on the frame (24).

Description

Exposure method and apparatus, and device manufacturing method

The present invention relates to an exposure technique for exposing a pattern on an object via a projection system, and a device manufacturing technique for manufacturing a device using this exposure technique.

In an exposure apparatus such as a so-called stepper or scanning stepper used in a photolithography process for producing a microdevice (electronic device) such as a semiconductor element or a liquid crystal display element, the depth of focus of the projection optical system is narrow and the exposure target Since there is a step (unevenness) on the surface of the substrate, the height (surface position) of the substrate surface is measured by an autofocus sensor (hereinafter referred to as an AF system), and the substrate surface of the projection optical system is measured based on the measurement result. The stage holding the substrate is controlled so as to be adjusted (focused) on the image plane. As a conventional AF system, for example, in order to suppress the influence of a slight position fluctuation of an optical member due to a disturbance or a fluctuation of an optical path due to a temperature fluctuation of an atmosphere on the optical path of the detection light, the detection light reflected on the surface to be measured For example, an oblique incidence AF system that receives reference light reflected by a reference surface formed on one surface of a predetermined prism and detects the surface position of the test surface with reference to the reference surface is used. (For example, refer to Patent Document 1).

In addition, the position of the stage that moves the substrate is conventionally measured by a laser interferometer. However, in a laser interferometer, short-term fluctuations in measured values due to temperature fluctuations in the atmosphere on the optical path of the measurement beam are observed. It can no longer be ignored. Therefore, as a measurement device that is superior in short-term stability of measurement values compared to laser interferometers and has a resolution close to that of laser interferometers, the diffraction grating scale is irradiated with detection light from the detection head, and the scale An encoder-type measuring device that detects the position of the scale in the periodic direction by detecting diffracted light from the light source is proposed (for example, Patent Document 2 and US Pat. No. 5,610,715 corresponding thereto) Refer to the book). There has also been proposed a measuring device that uses the scale to detect the position of the scale in the normal direction (see, for example, Patent Document 3).

JP 2008-042183 A JP 7-270122 A JP 2009-054734 A

As described above, for example, the influence of the temperature fluctuation of the atmosphere can be reduced by using an AF system and an encoder type measuring device using a reference surface formed on a prism. However, in the AF system, for example, if the height of the prism, and hence the reference surface, varies slightly due to disturbance or the like, the measurement result of the surface position of the surface to be measured changes accordingly, and the focusing accuracy may be reduced. There is.

One of the methods for reducing the influence of such slight variations in the height of the reference plane is to increase the frequency of calibration of measurement values of the AF system by, for example, test prints. In this case, exposure is performed. The process throughput is reduced.
In view of such circumstances, the aspect of the present invention reduces the influence of the temperature fluctuation of the atmosphere when exposing an object, and measures the position of the moving body that moves the object and the surface position of the object with high accuracy. The purpose is to do.

An exposure apparatus according to a first aspect of the present invention is an exposure apparatus that exposes a pattern onto an object via a projection system, a stage that holds the object and moves relative to the projection system, and the projection system A frame member that is supported in a stationary state and has a diffraction grating-like scale formed so as to face the stage, and is arranged on the stage, and each stage is irradiated with detection light, and the stage and the frame member A plurality of detection heads for detecting relative position information, a reference surface formed on the frame member, a first light flux on the reference surface, a second light flux on the surface of the object, A surface position detecting device that measures position information of the surface of the object in the direction along the optical axis of the projection system with reference to the reference surface.

An exposure apparatus according to the second aspect of the present invention, in an exposure apparatus that exposes a pattern on an object via a projection system, holds the object and moves relative to the projection system. A stage having a diffraction grating-like scale formed on the opposite side, a frame member supported in a stationary state with respect to the projection system, and a frame member arranged so as to face the stage. A plurality of detection heads for irradiating detection light to detect relative position information between the stage and the frame member, a reference surface formed on the frame member, and a first light flux on the reference surface, A surface position detecting device that irradiates the surface of the object with a second light flux and measures positional information of the surface of the object along the optical axis of the projection system with reference to the reference surface. It is intended.

An exposure method according to a third aspect of the present invention is an exposure method in which a pattern is exposed on an object via a projection system, the object is held on a stage that moves relative to the projection system, and the projection system On the other hand, the frame member supported in a stationary state is irradiated with detection light from the stage on the diffraction grating scale formed so as to face the stage, and the relative position between the stage and the frame member Information is detected, a first light beam is irradiated on a reference surface formed on the frame member, a second light beam is irradiated on the surface of the object, and the projection system of the surface of the object is used with reference to the reference surface. The position information in the direction along the optical axis is measured.

An exposure method according to the fourth aspect of the present invention is an exposure method in which a pattern is exposed on an object via a projection system. The exposure method moves to the projection system and has a stage on which a diffraction grating scale is formed. The object is held, and the scale member is irradiated with detection light from a frame member supported in a stationary state with respect to the projection system to detect relative position information between the stage and the frame member. The formed reference surface is irradiated with the first light beam, the surface of the object is irradiated with the second light beam, and the position of the surface of the object in the direction along the optical axis of the projection system with reference to the reference surface Information is measured.

A device manufacturing method according to the fifth aspect of the present invention uses the exposure apparatus according to the first or second aspect of the present invention, or the exposure method according to the third or fourth aspect of the present invention. Exposing a pattern to a substrate and processing the substrate on which the pattern has been exposed.

According to the aspect of the present invention, the surface position of the object surface (position in the optical axis direction of the projection system) is measured with reference to the reference surface formed on the frame member provided with the scale or the detection head. Further, the position information of the stage holding the object is measured by the encoder method through the frame member. Since the measurement is performed based on the frame member in common as described above, the surface position of the object with respect to the stage is highly accurate even if the position of the frame member fluctuates by using the difference between the measured values of the two, for example. Can be measured. Therefore, when the object is exposed, the influence of the temperature fluctuation of the atmosphere can be reduced, and the position of the stage and the surface position of the object can be measured with high accuracy.

1 is a partially cutaway view showing a schematic configuration of an exposure apparatus according to a first embodiment. It is a bottom view which shows the flame | frame 24 for scale board fixation in FIG. It is sectional drawing along the optical path of the measurement beam of FIG. 2, and a reference beam. (A) is a bottom view showing the frame 24 below the wafer alignment system ALG in FIG. 1, (B) is a cross-sectional view taken along line BB in FIG. 4 (A), and (C) is wafer stage WSB in FIG. FIG. It is a flowchart which shows an example of the exposure operation | movement of embodiment. It is sectional drawing which shows the principal part of AF type | system | group unit of a 1st modification. (A) is sectional drawing which shows the principal part of the AF type | system | group unit which concerns on a 2nd modification, (B) is sectional drawing which shows the state which moved the wafer stage WSA in the Y direction from the state of FIG. 7 (A). . It is the figure which notched some showing the schematic structure of the exposure apparatus which concerns on 2nd Embodiment. It is a flowchart which shows an example of the manufacturing process of an electronic device.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of an exposure apparatus 10 according to the present embodiment. The exposure apparatus 10 is a scanning exposure apparatus composed of a scanning stepper (scanner), and is a twin wafer stage type including two wafer stages WSA and WSB. The exposure apparatus 10 is installed in a box-shaped chamber (not shown) in which a temperature-controlled and highly dust-proof gas (for example, dry air) is supplied by a downflow method. In the present embodiment, a projection system (projection optical system) PL is provided. Hereinafter, the Z-axis is taken in parallel with the optical axis AX of the projection system PL, and the X-axis is taken in the direction in which the reticle and the wafer are relatively scanned in a plane perpendicular to the optical axis AX (direction parallel to the paper surface of FIG. 1). The Y axis is taken in the direction perpendicular to the Z axis and the X axis (the direction perpendicular to the paper surface of FIG. 1), and the rotation (tilt) directions around the X axis, Y axis, and Z axis are respectively θx, θy, and θz. The direction is described. In the present embodiment, the XY plane is substantially parallel to the horizontal plane.

In FIG. 1, an exposure apparatus 10 includes an illumination system ILS similar to that disclosed in, for example, US Patent Application Publication No. 2003/0025890, and an ArF excimer laser (wavelength 193 nm) from the illumination system ILS. A reticle stage RST that holds a reticle R illuminated by illumination light (exposure light) IL such as a KrF excimer laser (wavelength 248 nm) or a bright line of a discharge lamp, and the illumination light IL emitted from the reticle R is a wafer W1. (Or W2) Projection system PL to project on, first wafer stage WSA that moves while holding wafer W1, second wafer stage WSB that moves while holding wafer W2, and position measurement of wafer stages WSA and WSB System, wafer stage WSA, WSB drive mechanism (not shown), wafer stage WSA A first control system 6A (see FIG. 3) for controlling the operation, a second control system 6B for controlling the operation of the wafer stage WSB, a main control system 4 (see FIG. 3) for comprehensively controlling the operation of the entire apparatus, etc. It has. Further, the exposure apparatus 10 includes, for example, a wafer alignment system ALG made up of, for example, an image processing type FIA (Field Image 配置 Alignment) system arranged at a predetermined distance from the projection system PL in the X direction, and the projection system PL and the wafer alignment system ALG. And an AF system that measures a focus position or a Z position that is a position (plane position) in a direction parallel to the optical axis AX of the projection system PL on the surfaces of the wafers W1 and W2 on the wafer stages WSA and WSB. An AF system (autofocus sensor) including the unit 36 is provided.

On reticle stage RST in FIG. 1, reticle R having a circuit pattern or the like formed on its pattern surface (lower surface) is fixed, for example, by vacuum suction. The reticle stage RST can be driven minutely in the XY plane by a drive system (not shown) including a linear motor, for example, and can be driven at a scanning speed specified in the scanning direction (X direction). Position information including the X- and Y-direction positions in the moving plane of the reticle stage RST and the rotation angle in the θz direction is always detected by a laser interferometer (not shown) with a resolution of about 0.5 to 0.1 nm, for example. The A reticle stage control system (not shown) connected to a main control system (not shown) controls the operation of reticle stage RST via the drive system based on the position information.

Note that the projection magnification β of the projection system PL of the present embodiment is a reduction magnification of, for example, 1/4, 1/5, and the measurement error of the position information of the reticle stage RST is the projection magnification β on the image plane side of the projection system PL. Therefore, the influence is reduced. However, the position information of reticle stage RST may also be measured by an encoder-type measuring device described later.
In FIG. 1, a thick plate-like optical system frame 18 is disposed below the reticle stage RST in parallel to the XY plane. The optical system frame 18 covers the chain 21 on the upper body column 11 with a dust-proof bellows 22, respectively. It is supported by being suspended via a plurality of formed

suspension mechanisms

20A, 20B, 20C and the like. With this configuration, the optical system frame 18 is stably supported with little influence from disturbance. A first opening and a second opening are formed in the optical system frame 18 at a predetermined interval in the X direction, and a projection system PL and a wafer alignment system ALG are installed in the first opening and the second opening, respectively. The flange portion of the wafer alignment system ALG is fixed to the upper surface of the optical system frame 18.

Also, a scale plate fixing frame 24 having a flat plate-like opening through which the projection system PL and the wafer alignment system ALG are passed is stably supported on the bottom surface of the optical system frame 18 via a plurality of link mechanisms 32. . Accordingly, the frame 24 is supported in a stationary state relative to the projection system PL and the wafer alignment system ALG. The optical system frame 18, the link mechanism 32, and the frame 24 are each formed of a material (for example, Invar) having a very small linear expansion coefficient. The frame 24 can also be formed from low expansion glass, low expansion glass ceramic (for example, ZERODUR (trade name) of Shot Co.), low expansion ceramic, or Super Invar, which has a smaller linear expansion coefficient. It is.

A reflection type diffraction grating X scale having a predetermined pitch in the X direction and a reflection type diffraction grating Y scale having a predetermined pitch in the Y direction in a region on the + X direction side from the optical axis AX on the bottom surface of the frame 24; Is fixed in a scale plate 26A, and is a slit-shaped recess having a predetermined width in the X direction along the Y axis at a substantially intermediate position between the projection system PL and the wafer alignment system ALG on the bottom surface of the frame 24. 24a is formed. A region between the optical axis AX and the concave portion 24a on the bottom surface of the frame 24, a region between the concave portion 24a and the optical axis of the wafer alignment system ALG, and a region on the −X direction side from the optical axis of the wafer alignment system ALG,

Scale plates

26B, 26C, and 26D on which X scale and Y scale similar to the scale plate 26A are formed are fixed.

The scale plates 26A to 26D are, for example, thin flat glass plates, and the pitch (cycle) of the X scale and Y scale formed on the surface thereof is, for example, in the range of 138 nm to 4 μm, for example, about 1 μm. An encoder-type measuring device (hereinafter referred to as an encoder system, which will be described later in detail) that measures positional information of the wafer stages WSA and WSB from the scale plates 26A to 26D and the detection heads 28A and 28B on the wafer stages WSA and WSB. Is configured.

Further, as shown in FIG. 2 which is a bottom view of a part of the frame 24 in FIG. 1, the

scale plates

26B and 26C in FIG. It is divided into two scale plates 26C1 and 26C2. Similarly, the

other scale plates

26A and 26D in FIG. 1 are also divided into two scale plates having a symmetrical shape in the Y direction. The number of divisions of each of the scale plates 26A to 26D is arbitrary, and each of the scale plates 26A to 26D may be formed from one scale plate. In FIG. 2, the detection area ALW of the wafer alignment system ALG is shown, but the mechanism around the wafer alignment system ALG is shown in a simplified manner.

As the projection system PL in FIG. 1, for example, a double-sided telecentric refractive optical system including a plurality of lens elements arranged along the optical axis AX is used. When the illumination area of the reticle R is illuminated by the illumination light IL from the illumination system ILS, the image of the circuit pattern in the illumination area is passed through the projection system PL by the illumination light IL that has passed through the reticle R. Or, it is formed in an exposure region ILW (region conjugate to the illumination region) (see FIG. 2) elongated in the Y direction on W2. Wafers W1 and W2 are obtained by applying a photoresist (photosensitive agent) to the surface of a disk-shaped substrate having a diameter of, for example, 200 mm to 450 mm, such as silicon or SOI (silicon ion insulator). A catadioptric system can also be used as the projection system PL.

When the exposure apparatus 10 performs exposure by applying a liquid immersion method, a liquid (pure liquid) that transmits the illumination light IL between the projection system PL and the wafers W1 and W2 by a local liquid immersion mechanism (not shown). Water). As the local immersion mechanism, an immersion mechanism disclosed in, for example, US Patent Application Publication No. 2007/242247 or European Patent Application Publication No. 1420298 can be used. In addition, when the exposure apparatus 10 is a dry type, it is not necessary to provide the local liquid immersion mechanism.

Wafer stages WSA and WSB are supported in a non-contact manner on an upper surface parallel to the XY plane of base member 12 through a clearance of about several μm, for example, via an air pad that constitutes a vacuum preload type aerostatic bearing. Wafer tables 14A and 14B for holding wafers W1 and W2 by vacuum suction or the like via a wafer holder (not shown) are stacked on XY stages 16A and 16B. The shape of wafer tables 14A and 14B viewed from above is substantially square. As an example, the XY stages 16A and 16B are driven on the base member 12 in the X direction, the Y direction, and the θz direction by a planar motor 44A or the like (see FIG. 3). Further, the wafer tables 14A and 14B include a focus leveling mechanism 46A and the like (see FIG. 3) for controlling the Z position of the wafers W1 and W2 and the inclination angles in the θx direction and the θy direction, respectively. Further, the wafer tables 14A and 14B are provided with an aerial image measurement system (not shown) that detects an image such as an alignment mark of the reticle R or an evaluation line and space pattern through a predetermined slit pattern.

Further, as shown in FIG. 4C, reference mark plates 48B1, 48B2, and 48B3 on which reference marks (not shown) are formed, for example, at three positions on the wafer table 14B of the wafer stage WSB are fixed. Similarly, three reference mark plates (not shown) are also fixed on the wafer table 14A of the wafer stage WSA. The reference marks are detected by the wafer alignment system ALG, and the relationship between the reference marks and the corresponding slit pattern of the aerial image measurement system is stored in the storage device of the main control system 4.

In FIG. 1, detection heads 28A, 29A, 30A and 31A for detecting the scales and scale forming surfaces of the scale plates 26A to 26D are fixed to four corners on the wafer table 14A. Similarly, detection heads 28B, 29B, 30B, and 31B (see FIG. 4C) for detecting scales and scale forming surfaces of the scale plates 26A to 26D are fixed to four corners on the wafer table 14B. . The detection heads 28A and 28B respectively detect the X-direction position of the X scale in the scale plates 26A to 26D, and detect the Y-direction position of the Y scale in the scale plates 26A to 26D. The heads 28AY and 28BY and Z heads 28AZ and 28BZ for detecting the position (Z position) in the Z direction of the scale forming surfaces of the scale plates 26A to 26D are configured. Similarly, the other three detection heads 29A to 31A and 29B to 31B on the wafer tables 14A and 14B are respectively provided with an X head, a Y head, and a Z head. In FIG. 1, only the Z heads 30AZ, 28BZ, and 30BZ in the detection heads 30A, 28B, and 30B are shown.

In this case, the X head 28AX and the Y head 28AY respectively irradiate the X scale and Y scale in the scale plates 26A to 26D with detection light made of laser light, and detect interference light due to diffracted light generated at the corresponding scale. Thus, the position in the X direction and the Y direction of the wafer table 14A (wafer stage WSA), which is the relative displacement (relative position) in the X direction and the Y direction of the scale, is detected with a resolution of about 0.5 to 0.1 nm, for example. . Detailed configurations of the X head 28AX and the Y head 28AY are disclosed in, for example, US Pat. No. 5,610,715 (and corresponding JP-A-7-270122).

Further, of the detection heads 28A to 31A (or 28B to 31B) on the wafer stage WSA (or WSB), at least two X heads and two Y heads irradiate one of the scale plates 26A to 26D with detection light. Thus, the positions of the wafer stage WSA (WSB) in the X direction and the Y direction are measured. Therefore, the rotation angle in the θz direction of wafer stage WSA (WSB) can be obtained from the two positions in the X direction or Y direction.

Further, as an example, the Z head 28AZ irradiates the scale forming surfaces of the scale plates 26A to 26D with the detection light and detects the reflected light as in the case of the optical pickup, thereby detecting the relative Z position of the scale forming surface. For example, the Z position of the wafer table 14A is detected with a resolution of about 0.1 μm. A detailed configuration of the Z head 28AZ is disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-54734.

Further, all the Z heads of the detection heads 28A to 31A (or 28B to 31B) on the wafer stage WSA (or WSB) constantly irradiate one of the scale plates 26A to 26D with detection light, so that the wafer stage WSA ( WSB) Z position is measured. Therefore, the rotation angles of the wafer table 14A (14B) in the θx direction and the θy direction can be obtained from the four Z positions.

Therefore, by the encoder system including the scale plates 26A to 26D and the detection heads 28A to 31A, the positions of the first wafer stage WSA (wafer table 14A) in the X, Y, and Z directions, and the θx, θy, and θz directions. It is possible to measure position information of 6 degrees of freedom consisting of the rotation angle of the direction. Similarly, position information of six degrees of freedom of the second wafer stage WSB (wafer table 14B) can be measured by an encoder system including the scale plates 26A to 26D and the detection heads 28B to 31B.

Further, detection signals of the detection heads 28A to 31A on the wafer stage WSA (an X measurement signal SX that is a detection signal of the X head, a Y measurement signal SY that is a detection signal of the Y head, and a Z measurement signal that is a detection signal of the Z head) SZ) is supplied to the stage control system 40A of FIG. 3. The stage control system 40A obtains position information of the six degrees of freedom of the wafer stage WSA, and based on these position information and control information from the control system 6A. The operations of the planar motor 44A and the focus leveling mechanism 46A are controlled. Detection signals from the detection heads 28B to 31B of the wafer stage WSB are also processed by a similar stage control system (not shown).

Next, the AF system including the AF system unit 36 will be described. First, in FIG. 1, an AF-based reference surface 34 made of, for example, a highly reflective metal film is formed on the surface of the recess 24a of the frame 24. As shown in FIG. 2, the reference surface 34 is formed at the center in the Y direction of the recess 24 a of the frame 24. Further, an AF light transmission system 36A that irradiates the reference surface 34 with the reference beam DLR and irradiates the measurement beam DL to the test surface facing the reference surface 34, and the reference beam DLR and measurement from the reference surface 34 and the test surface. An AF system unit 36 is composed of an AF light receiving system 36B that receives the beam DL.

FIG. 3 is a cross-sectional view taken along the reference plane 34 of the frame 24 of FIG. 2, and the Z position of the surface W1a (test surface) of the wafer W1 on the wafer stage WSA (wafer table 14A) is measured by the AF system. Indicates the state of In FIG. 3, the AF light transmission system 36A includes, for example, a beam generation unit (not shown) that generates a reference beam DLR and a measurement beam DL in a wavelength range that does not expose the photoresist on the wafer W1, and the reference beam DLR and the measurement beam. A light transmission lens 36Aa that condenses the DL and a first rhomboid prism 36Ab that shifts the optical paths of the reference beam DLR and the measurement beam DL in the −Z direction. The measurement beam DL projected obliquely downward from the AF light transmission system 36A forms, for example, slit images at a plurality of measurement points arranged at predetermined intervals in the Y direction on the surface W1a of the wafer W1, and is reflected by the surface W1a. The measured beam DL is directed to the AF light receiving system 36B. In addition, the reference beam DLR projected obliquely upward from the AF light transmission system 36A forms, for example, a slit image on the reference surface 34, and the reference beam DLR reflected by the reference surface 34 travels to the AF light receiving system 36B. The AF light transmission system 36A is provided with a vibrating mirror (not shown) that vibrates these slit images within a predetermined range in the Y direction and a herbing (not shown) that adjusts the positions of the slit images. .

The AF light receiving system 36B condenses the second rhomboid prism 36Bb that shifts the optical paths of the reference beam DLR and the measurement beam DL reflected by the surface W1a in the + Z direction, and the reference beam DLR and the measurement beam DL, respectively, and forms a slit image. A light-receiving lens 36Ba that re-forms and a photoelectric sensor 36Bc that detects the slit image thereof. The light receiving surface of the photoelectric sensor 36Bc, the reference surface 34, and the surface W1a are substantially conjugate. As the photoelectric sensor 36Bc, an array of a plurality of light receiving elements that detect the light amount of those slit images through a predetermined opening can be used. A plurality of detection signals of the photoelectric sensor 36Bc are supplied to the signal processing unit 36C.

For example, the signal processing unit 36C synchronously rectifies the plurality of detection signals using a driving signal of a vibrating mirror (not shown) in the AF light transmission system 36A, thereby corresponding to the Z positions of the slit images. Generate a measurement signal. Furthermore, the signal processing unit 36C subtracts the measurement signal corresponding to the Z position of the slit image on the reference surface 34 from the measurement signal corresponding to the Z position of the plurality of slit images projected to the plurality of measurement points on the surface W1a. Using the Z position of the reference surface 34 as a reference, a Z position measurement signal AFW for the test surface indicating the Z positions Z1j (j = 1 to J: J is an integer of 2 or more) of a plurality of measurement points on the surface W1a is generated. Note that the actually measured Z position Z1j is, for example, a value obtained by subtracting a predetermined offset from the Z-direction interval between the reference surface 34 and the test surface. As described above, since the reference plane 34 is used as a reference, when the optical paths of the measurement beam DL and the reference beam DLR change in the same manner due to disturbances or temperature fluctuations in the atmosphere, there is no drift in the measurement value, and the measurement surface DL The Z position can be measured with high accuracy. The Z position measurement signal AFW is supplied to the calculation unit 38A and the storage unit 42A.

The AF system includes the oblique incidence AF system unit 36 and the signal processing unit 36C. A more detailed configuration of the AF system unit 36 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-042183.
In addition, the wafer stage WSA is driven in the X direction and the Y direction, and the surface W1a of the wafer W1 is scanned over the measurement region on which a plurality of slit images are projected by the measurement beam DL. The Z position Z1i (i = 1 to I: I is an integer greater than or equal to 2 × J) is measured by the AF system at each of a large number of evaluation points arranged in a grid at predetermined intervals in the direction and the Y direction.

Further, in FIG. 3, the detection head 31A of the wafer stage WSA (wafer table 14A) irradiates the scale plate 26C2 with detection light, and the X head and the Y head in the detection head 31A move the wafer table 14A to the scale plate 26C2. An X measurement signal SX and a Y measurement signal SY indicating positions in the X direction and the Y direction are supplied to the stage control system 40A. A Z measurement signal SZ indicating the Z position of the wafer table 14A relative to the scale plate 26C2 is supplied from the Z head 31AZ in the detection head 31A to the arithmetic unit 38A and the stage control system 40A. Similarly, the X measurement signal and the Y measurement signal are supplied to the stage control system 40A from the other detection heads 28A to 30A on the wafer stage WSA, respectively, and the Z measurement signal is supplied to the arithmetic unit 38A and the stage control system 40A. Yes.

In this case, it corresponds to the i-th evaluation point on the surface W1a on an average plane passing through the Z position measured by the Z sensors of the detection heads 28A to 31A (hereinafter referred to as the stage surface of the wafer table 14A). Assuming that the Z position of the point is Z2i and the known offset of the Z position between the surface of the scale plates 26A to 26D of the frame 24 and the reference plane 34 is ZAof, the calculation unit 38A performs an operation including the following difference calculation as an example, The Z position ΔZSWi at the i-th evaluation point on the surface W1a with respect to the stage surface of the wafer table 14A is calculated. The calculation result of the Z position ΔZSWi at all the evaluation points on the surface W1a is stored in the storage unit 42A. The offset ZAof may use an actual measurement value, for example.

ΔZSWi = Z1i− (Z2i + ZAof) (1)
As can be seen from this equation (1), the AF system measures the Z position of the surface W1a with reference to the reference surface 34 of the frame 24, and the detection heads 28A to 31A (Z heads) are also provided on the scale plates 26A to 26A. Since the Z position of the wafer table 14A with respect to 26D is measured, even if the Z position of the frame 24 slightly fluctuates due to disturbance or the like, the measured value of the Z position of the surface W1a with respect to the stage surface of the wafer table 14A does not change. . Therefore, the relative Z position (ΔZSWi) of the surface W1a with respect to the wafer table 14A can always be measured with high accuracy.

At the time of subsequent exposure, in FIG. 1, the Z head Z of the detection heads 28A to 31A, etc. is used as a reference for the scale plates 26A to 26D, and the Z position Z3i of the wafer table 14A (the position corresponding to the i th evaluation point on the wafer W1). The Z position is measured, and the measurement result is supplied to the stage control system 40A. The stage control system 40A is also supplied with the Z position ΔZSWi of equation (1) measured for all evaluation points on the wafer W1 from the storage unit 42A. Further, information on the Z position ZPL of the image plane of the projection system PL with reference to the scale plates 26A to 26D is supplied in advance from the control system 6A to the stage control system 40A. The stage control system 40A subtracts the Z position ZPL of the image plane from the sum of the Z position Z3i measured by the encoder system and the Z position ΔZSWi of the evaluation point on the wafer W1 as follows, thereby evaluating the wafer W1. A defocus amount ΔFi from the image plane at the Z position of the point is obtained.

ΔFi = (Z3i + ΔZSWi) −ZPL (2)
Note that the Z position ZPL of the image plane of the projection system PL in Expression (2) is actually the contrast of the image of a predetermined evaluation pattern measured by, for example, an aerial image measurement system (not shown) in the wafer stage WSA. It can be obtained from the Z position (Z position measured by the detection heads 28A to 31A) Z30 of the stage surface of the wafer table 14A at the maximum.

Then, the stage control system 40A drives the focus leveling mechanism 46A in the wafer table 14A so that the defocus amount ΔFi of each evaluation point on the wafer W1 in the exposure area of the projection system PL is minimized as a whole. Thus, the surface of the wafer W1 during scanning exposure is accurately focused on the image plane of the projection system PL, and the pattern image of the reticle R is exposed to each shot area of the wafer W1 with high accuracy.

The operation of focusing the surface of the wafer W1 on the image plane of the projection system PL based on the measurement of the Z position of the surface of the wafer W1 by the AF system and the measurement results of the detection heads 28A to 31A at the time of exposure is as follows. The same applies to the wafer W2 on the second wafer stage WSB.
4A is a bottom view showing the wafer alignment system ALG in FIG. 1, FIG. 4B is a cross-sectional view taken along line BB in FIG. 4A, and FIG. 4C is the wafer stage in FIG. It is a top view which shows WSB.

4A, a pair of

elongated recesses

24b and 24c are formed on the bottom surface of the frame 24 so as to sandwich the wafer alignment system ALG in a direction intersecting the X axis at 45 °, and the centers of the

recesses

24b and 24c are formed. Reference surfaces 34A1 and 34A2 made of a highly reflective metal film are formed in the portion. The rhomboid prisms 50Ab, 50Ac and 50Bb, 50Bc for light transmission and reception are fixed to a pair of through holes of the frame 24 formed so as to sandwich the reference surfaces 34A1, 34A2 in the

recesses

24b, 24c. Yes.

As shown in FIG. 4B, an optical system 50Aa including a light transmitting lens and the like, a rhombus prism 50Ab, a rhombus prism 50Ac, and an optical system 50Ad including a light receiving lens and the like are similar to the AF system unit 36 in FIG. 1 is an oblique incidence AF system unit 50A. The reference beam DLRA and the measurement beam DLA projected from the rhomboid prism 50Ab of the AF system unit 50A form a slit image on the reference surface 34A1 of the frame 24 and the surface of the wafer W2 (region facing the reference surface 34A1), respectively. Reflected light from the surfaces of the 34A1 and the wafer W2 is received through the rhombus prism 50Ac. Then, the detection signal output from the optical system 50Ad is processed by a signal processing unit (not shown) similar to the signal processing unit 36C of FIG. 3, thereby tilting the Z position of the surface of the wafer W2 with reference to the reference surface 34A1. Can be measured by the incident method.

Similarly, a second oblique incidence AF system unit 50B similar to the AF system unit 50A is configured including the rhomboid prisms 50Bb and 50Bc. The AF system unit 50B projects the reference beam and the measurement beam onto the reference surface 34A2 of the frame 24 and the surface of the wafer W2 corresponding to the reference surface 34A2, and the Z position on the surface of the wafer W2 is obliquely incident on the basis of the reference surface 34A2. measure. Two AF systems for the wafer alignment system ALG are configured including the

AF system units

50A and 50B and a signal processing unit (not shown). For example, the Z position ZAL1 on the center (optical axis) of the detection area ALW of the wafer alignment system ALG can be obtained by averaging the Z positions obtained at the two positions corresponding to the reference surfaces 34A1 and 34A2. .

Also in this case, the Z heads 28BZ and the like of the detection heads 28B to 31B in FIG. 4C irradiate the

scale plates

26C and 26D on the bottom surface of the frame 24 around the wafer alignment system ALG with the detection light, thereby The Z position of wafer stage WSB (wafer table 14B) is measured with reference to 26C and 26D. An average surface passing through these Z positions is referred to as a stage surface of the wafer table 14B. Therefore, the measurement values of the detection heads 28B to 31B are calculated from the Z position ZAL1 obtained by the

AF system units

50A and 50B by the calculation unit (not shown) similar to the calculation unit 38A of FIG. The wafer table at the center of the detection area ALW is subtracted by subtracting the sum of the Z position ZAL2 at the center of the detection area ALW on the surface defined by (1) and the steps at the Z position from the

scale plates

26C, 26D to the reference planes 34A1, 34A2. The Z position ΔZB of the surface of the wafer W2 with respect to the stage surface 14B can be obtained. The Z position ΔZB is also maintained at the same value even if the Z position of the frame 24 fluctuates, and therefore always represents the Z position of the surface of the wafer W2 with respect to the stage surface with high accuracy.

Therefore, the value ZAL2 of the Z position ZAL2 when the stage surface of the wafer table 14B previously matches the best focus position of the wafer alignment system ALG (for example, the position where the contrast of the image of the mark imaged by the wafer alignment system ALG is maximized). 'Is obtained, and the defocus amount for the wafer alignment system ALG on the surface of the wafer W2 is obtained by subtracting the value ZAL2' from the sum of the Z position ΔZB and the Z position ZLA2. By driving the focus leveling mechanism of the wafer table 14B so that the defocus amount becomes 0, the alignment mark (hereinafter referred to as a wafer mark) to be measured on the wafer W2 by the wafer alignment system ALG is always in the best focus state. The position can be measured. Therefore, from this measurement result, the alignment control system (not shown) in the main control system 4 is on the wafer W2 on the coordinate system determined by the reference marks of the reference mark plates 48B1 to 48B3 on the wafer table 14B by, for example, the EGA method. The array coordinates of each shot area can be obtained. Such alignment can be similarly performed on the wafer W1 on the wafer stage WSA.

Next, an example of the exposure operation of the exposure apparatus 10 of the present embodiment will be described with reference to the flowchart of FIG. This exposure operation is controlled by the main control system 4. First, in step 102 in FIG. 5, the first wafer stage WSA is moved to the loading position in the −X direction in FIG. 1, and a wafer (referred to as W1) is loaded on the wafer stage WSA. The X and Y heads of the detection heads 28A to 31A continuously measure the positions of the wafer stage WSA in the X and Y directions. At this time, the second wafer stage WSB is retracted in the + Y direction, for example. Further, the wafer stage WSA is driven in the X direction and the Y direction, and the position of a predetermined reference mark on the reference mark plates (members corresponding to the reference mark plates 48B1 to 48B3 in FIG. 4C) on the wafer table 14A. Is measured by the wafer alignment system ALG, and based on the measurement result, the rotation angle of the wafer table 14A in the θz direction is reset, and the origin of the coordinate system above it is set.

In the next step 104, the wafer stage WSA is driven in the X direction and the Y direction, and the first measurement target wafer mark on the wafer W1 is moved into the detection area of the wafer alignment system ALG, as shown in FIG. The alignment AF system including the

AF system units

50A and 50B measures the Z position (focus position) of the wafer W1 on the wafer stage WSA with reference to the AF system reference surfaces 34A1 and 34A2 provided on the frame 24. At this time, the Z position of the detection heads 28A to 31A is also measured based on the

scale plates

26C and 26D, and the Z position of the wafer W1 with respect to the stage surface of the wafer table 14A is obtained based on the difference between the Z positions. .

In the next step 106, the wafer alignment system ALG is passed through the wafer table 14A so that the difference (defocus amount) between the Z position obtained in step 104 and the best focus position of the wafer alignment system ALG becomes zero. The surface of the wafer W1 is focused by the autofocus method, and the wafer mark on the wafer W1 is detected by the wafer alignment system ALG. Actually, steps 104 and 106 are executed for each wafer mark to be measured on the wafer W1. Based on the measured positions of all the wafer marks, the arrangement coordinates of all shot areas of the wafer W1 are calculated (alignment of the wafer W1).

In the next step 108, the wafer stage WSA is moved in the + X direction, and the Z position (focus) of the surface of the wafer W1 with reference to the reference plane 34 of the AF system of the frame 24 by the AF system including the AF system unit 36 in the middle. Position) distribution. In parallel with this operation, the Z position of the wafer table 14A (wafer stage WSA) with respect to the

scale plates

26B and 26C is measured by the Z heads of the detection heads 28A to 31A of the encoder system of the wafer stage WSA. The Z position ΔZSWi at all evaluation points on the surface of the wafer W1 with respect to the stage surface of 14A is calculated. The calculation result is stored in the storage unit 42A.

In the next step 110, the wafer stage WSA is moved below the projection system PL. In the next step 112, the wafer stage WSA is moved stepwise in the X and Y directions based on the alignment result of the wafer W1, and one shot area on the wafer W1 is moved to the scanning start position. Thereafter, the stage control system 40A continues to measure the Z position with respect to the

scale plates

26A and 26B by the Z heads of the detection heads 28A to 31A, and the stage control system 40A stores the measured value of the Z position and the wafer W1 stored in step 108. The defocus amount ΔFi from the image plane of the surface of the wafer W1 in the exposure area of the projection system PL is obtained from the equation (2) using the Z positions (focus positions) of a large number of evaluation points on the surface. Further, the stage control system 40A drives the focus leveling mechanism 46A according to the defocus amount ΔFi to focus the surface of the shot area of the wafer W1 on the image plane.

In step 112, with the shot area of the wafer W1 in focus, the reticle stage RST and the wafer stage WSA are exposed while exposing the shot area with an image of the projection system PL of a part of the pattern of the reticle R. Are scanned in the Y direction in synchronization with the projection system PL, so that the image of the pattern of the reticle R is scanned and exposed in the shot area. Thereafter, the operations of

steps

112 and 114 are repeated by the step-and-scan method for each shot area to be exposed on the wafer W1. When the exposure of all the shot areas on the wafer W1 is completed, the operation moves to step 116, the wafer stage WSA moves to the + X direction unloading position, and the wafer W1 is unloaded.

In the next step 118, if the wafer to be exposed remains, the operation returns to step 102, and steps 102 to 116 are repeated in the wafer stage WSA to perform alignment and exposure for the next wafer. Further, almost in parallel with the operations of steps 110 to 116 of the first wafer stage WSA, on the second wafer stage WSB side, steps 102B (loading of wafer W2) and steps 104B similar to the operations of steps 102 to 108 are performed. (Measurement of the Z position of the wafer W2 by the AF system for alignment, etc.), step 106B (alignment of the wafer W2 while focusing the wafer W2 on the wafer alignment system ALG), and step 108B (AF system and detection) The operation of measuring and storing the Z positions of many evaluation points on the wafer W2 by the Z heads of the heads 28B to 31B is executed.

Further, almost in parallel with the operation of steps 102 to 108 on the first wafer stage WSA side, on the second wafer stage WSB side, the same step 110B as the operation of steps 110 to 116 (projection system PL side of the wafer stage WSB). ), Step 112B (measurement of the Z position of the wafer W2 and focusing of the shot area), step 114B (scan exposure of the shot area), and step 116B (unload of the wafer W2) are executed. . If the wafer to be exposed remains in the next step 118B, the operations from step 102B to step 116B are repeated on the wafer stage WSB side. In this way, by performing the alignment by the wafer alignment system ALG (step 106 or 106B) and the exposure by the projection system PL (step 114B or 114) almost in parallel by the twin wafer stage method, for example, one lot of wafers can be increased. Exposure is possible with throughput.

Effects and the like of this embodiment are as follows.
(1) An exposure apparatus 10 of the present embodiment is a wafer that holds the wafer W1 and moves relative to the projection system PL in an exposure apparatus that exposes an image of the pattern of the reticle R on the wafer W1 via the projection system PL. A stage 24, a frame 24 on which scale plates 26A to 26D, which are supported in a stationary state with respect to the projection system PL and are formed with a diffraction grating-like scale so as to face the wafer stage WSA, are fixed to the wafer stage WSA. A plurality of detection heads 28A to 31A that are disposed and irradiate the scale with detection light to detect relative position information between the wafer stage WSA and the frame 24, a reference surface 34 formed on the frame 24, and a reference surface 34 Is irradiated with the reference beam DLR (first light beam), the surface of the wafer W1 is irradiated with the measurement beam DL (second light beam), and the reference surface 34 is used as a reference. AF system including AF system unit 36 for measuring the position along the optical axis of the projection system PL of the surface of the wafer W1 (surface position or Z position) and (surface position detecting device), and a.

Further, in the exposure method by the exposure apparatus 10, the wafer W1 is held on the wafer stage WSA moving with respect to the projection system PL (step 102) and fixed to the frame 24 supported in a stationary state with respect to the projection system PL. The diffraction grating scale formed on the scale plates 26A to 26D so as to face the wafer stage WSA is irradiated with detection light from the detection heads 28A to 31A of the wafer stage WSA, so that the relative relationship between the wafer stage WSA and the frame 24 is reached. Position information is detected (step 102, part of step 108, and step 112), the reference beam DLR is irradiated onto the reference surface 34 formed on the frame 24 by the AF system, and the measurement beam DL is irradiated onto the surface of the wafer W1. Then, the surface position (Z position) of the surface of the wafer W1 is measured using the reference surface 34 as a reference. (Part of step 108).

According to the present embodiment, the AF system measures the surface position (Z position) of the wafer W1 with reference to the reference surface 34 formed on the frame 24 provided with the scale. The encoder system including the detection heads 28A to 31A determines the position of the wafer stage WSA (wafer table 14A) in the X direction, the Y direction, and the Z position with reference to the scale plates 26A to 26D (scale forming surface) of the frame 24. measure. As described above, since the AF system and the encoder system commonly perform position measurement based on the frame 24, even if the Z position of the frame 24 varies by using the difference between the two measurement values, for example, the wafer stage WSA. The surface position of the wafer W1 can be measured with high accuracy. Therefore, when the wafer W1 is exposed, the influence of the temperature fluctuation of the atmosphere of the exposure apparatus 10 can be reduced, and the position of the wafer stage WSA and the surface position of the wafer W1 can be measured with high accuracy. Therefore, based on the measured value, the surface of the wafer W1 can be focused on the image plane of the projection system PL with high accuracy.

(2) The detection heads 28A to 31A have Z heads 28AZ and 30AZ, respectively. The Z heads 28AZ and the like are wafers that are relative positions of the wafer table 14A and the scale forming surface of the frame 24 in the optical axis AX direction. The Z position of the table 14A (wafer stage WSA) is measured. Accordingly, in step 108, when the Z position of the wafer W1 is measured by the AF system with reference to the reference surface 34 of the frame 24, the Z head of the wafer table 14A is referenced with the Z head 28AZ or the like and the scale surface of the frame 24 as a reference. By measuring the position and obtaining the difference between the two Z positions, the Z position of the surface of the wafer W1 relative to the wafer table 14A can be measured with high accuracy even if the Z position of the reference surface 34 changes.

The number of detection heads 28A to 31A is such that at least one X head 28AX and the like and at least two Y heads 28AY or the like, or at least two X heads and at least one Y head are scale plates 26A to 26D, respectively. It is arbitrary as long as the corresponding scale can be detected.
The number of Z heads 28AZ and the like in the detection heads 28A to 31A is preferably at least three. Thereby, the Z position of the wafer table 14A and the inclination angles in the θx direction and the θy direction can be measured. Note that there may be at least one Z head.

(3) The reference surface 34 is formed on the surface of the recess 24 a that is a recess with respect to the wafer stage WSA of the frame 24. Accordingly, the optical system of the AF system unit 36 that projects the reference beam DLR onto the reference surface 34 can be easily arranged.
If there is a sufficient space between the bottom surface of the frame 24 and the wafer stage WSA, the reference surface is formed on the bottom surface of the frame 24 (the same surface as the scale plates 26A to 26D) or the convex portion provided on the bottom surface of the frame 24. 34 may be formed.

(4) The exposure apparatus 10 moves independently while holding the wafer alignment system ALG (mark detection system) for detecting the position of the wafer mark on the wafers W1 and W2 and the wafers W1 and W2 to be exposed. A first wafer stage WSA and a second wafer stage WSB are provided, and an AF system unit 36 (optical system) of the AF system is disposed between the projection system PL and the wafer alignment system ALG. Wafer stage WSB also includes detection heads 28B-31B that measure the position of wafer stage WSB (wafer table 14B) using scale plates 26A-26D provided on frame 24.

Therefore, the position of the wafer mark on the wafer W2 on the wafer stage WSB can be measured by the wafer alignment system ALG while exposing the wafer W1 on the wafer stage WSA via the projection system PL. Thereby, the throughput of the exposure process can be improved. Furthermore, since the surface position distribution of the wafer W2 on the wafer stage WSB can be measured by the AF system while the wafer stage WSB is being moved from below the wafer alignment system ALG to below the projection system PL, the throughput is not reduced. The surface position distribution of the wafer W2 (same for the wafer W1) can be measured.

(5) The exposure apparatus 10 irradiates the reference surface 34A1 for the wafer alignment system ALG formed on the frame 24 and the reference beam DLRA (third light beam) to the reference surface 34A1, and the measurement beam is applied to the surface of the wafer W2. An alignment AF system unit 50A that irradiates DLA (fourth light beam) and measures the position (Z position) along the optical axis of the wafer alignment system ALG on the surface of the wafer W2 with reference to the reference surface 34A1. Including an AF system (a mark detection system surface position detection device). Accordingly, the wafer W2 can be focused on the wafer alignment system ALG with high accuracy using the AF system measurement result.

In the above embodiment, the following modifications are possible.
(1) In the above embodiment, the reference beam DLR from the AF system unit 36 is directly projected on the reference surface 34 of the frame 24. On the other hand, as a first modification, as shown in FIG. 6, the reference surface 34 formed in the recess 24a of the frame 24 has a trapezoidal cross-sectional shape with a long reference surface, and the surface on the reference surface side. May be provided with a prism 52 fixed to the reference surface 34. In FIG. 6, the rhomboid prism 36Ab (first deflecting member) in the AF light transmission system 36A and the rhombus prism 36Bb (second deflecting member) in the AF light receiving system 36B are respectively fixed in through holes provided in the frame 24. ing.

In the first modification, the reference beam DLR emitted from the rhomboid prism 36Ab is projected onto the reference surface 34 through the first inclined surface of the prism 52, and the reference beam DLR reflected by the reference surface 34 is converted into the prism 52. And enters the rhomboid prism 36Bb through the second inclined surface. Other configurations and operations are the same as those in the embodiment of FIG.
According to the first modification, the angle of the reference beam DLR emitted from the rhomboid prism 36Ab and incident on the rhombus prism 36Bb can be reduced, so that the configuration of the optical system of the AF system unit 36 is easy.

(2) Since the rhomboid prisms 36Ab and 36Bb are supported by the frame 24, the arrangement of the optical system of the AF system unit 36 is easy. One of the rhombus prisms 36Ab and 36Bb may be supported by the frame 24. Further, the AF system unit 36 may be configured without using the rhombus prisms 36Ab and 36Bb.
(3) Further, as shown in the second modified example of FIG. 7A, a reflecting surface 52R may be formed on the surface of the prism 52 that is fixed so as to cover the reference surface 34 and that faces the reference surface 34. . 7A, when the Z position of the surface of the wafer W1 with respect to the reference surface 34 is measured using the AF system unit 36, for example, the Z of the detection head 28A provided on the wafer table 14A of the wafer stage WSA. The head 28AZ irradiates the scale plate 26B1 with the detection light DA and measures the Z position of the wafer table 14A with respect to the scale plate 26B1. Subsequently, as shown in FIG. 7B, the wafer stage WSA is moved in the + Y direction, and the detection light DA of the Z head 28AZ is applied to the reflecting surface 52R of the prism 52, and the Z head 28AZ is used for the Z position. And the Z position of the upper surface of the Z head 28AZ may be measured by the AF system. In this case, since the Z-direction distance Z7B between the reflecting surface 52R and the reference surface 34 can be measured with high accuracy, the difference between the Z position measured by the Z head 28AZ and the Z position measured by the AF system is the distance Z7B. For example, the Z head 28AZ can be easily calibrated by adjusting the offset of the measured value of the Z head 28AZ.

(4) The AF system signal processing unit 36C of the above embodiment performs synchronous rectification. Instead, without providing a vibrating mirror in the AF light transmission system 36A, for example, a line sensor is used as the photoelectric sensor 36Bc, and the Z position of each measurement point is obtained from the position of the slit image formed on the line sensor. You may do it.
(5) As an encoder system using the scale plates 26A to 26D, a magnetic linear including a periodic magnetic scale in which a magnetic body whose polarity is reversed is formed at a minute pitch, and a magnetic head that reads the magnetic scale is used. It is also possible to use an encoder or the like.

(6) A laser interferometer for measuring the positions of the wafer stages WSA and WSB may be provided in parallel with the encoder system including the detection heads 28A to 31A.
(7) In the above embodiment, the present invention is applied to a twin wafer stage type exposure apparatus. However, the present invention can be similarly applied to an exposure apparatus having only one wafer stage. In this case, the AF system for the wafer may be disposed in the vicinity of the projection system PL, for example. At this time, the reference plane 34 for the AF system may be formed on the bottom surface of the frame 24 near the projection system PL.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, a detection head is provided on the frame side, and a scale is provided on the wafer stage WSA, WSB side. In FIG. 8, parts corresponding to those in FIG. Detailed description is omitted or simplified.

FIG. 8 shows an exposure apparatus 10A of the present embodiment. In FIG. 8, a flat frame 54 is stably supported via a plurality of link mechanisms 32 on the bottom surface of the optical system frame 18 that supports the projection system PL. The optical system frame 18 is supported on the base member 12 through an anti-vibration mechanism (not shown) as an example. Further, a plurality of detection heads 28C and 30C similar to the detection head 28A of FIG. 1 are fixed to the frame 54 so as to sandwich the projection system PL in the X direction, and the same as the detection head 28C so as to sandwich the projection system PL in the Y direction. A plurality of detection heads (not shown) are fixed. Further, a plurality of detection heads 28D and 30D similar to the detection head 28C are fixed to the frame 54 so as to sandwich the wafer alignment system ALG in the X direction, and the same as the detection head 28C so as to sandwich the wafer alignment system ALG in the Y direction. A plurality of detection heads (not shown) are fixed. Further, a reference surface 34 is formed in a recess on the bottom surface of the frame 54 between the projection system PL and the wafer alignment system ALG, and an AF system unit 36 is disposed so as to sandwich the reference surface in the Y direction. Includes an AF system.

Further, scale plates 26E1, 26E2 and the like having X scales and Y scales formed on the surfaces thereof, like the

scale plates

26A, 26B of FIG. 1, so as to surround the wafer W1 on the wafer table 14A of the first wafer stage WSA. Scale plates 26G1, 26G2, etc. with X scale and Y scale formed on the surface in the same manner as

scale plates

26C, 26D of FIG. 1 so as to surround wafer W2 on wafer table 14B of second wafer stage WSB. Is fixed. Other configurations are the same as those of the first embodiment.

The exposure method according to this embodiment is an exposure method in which a pattern is exposed on the wafer W1 via the projection system PL. The wafer W1 moves on the wafer stage WSA that moves relative to the projection system PL and has a diffraction grating scale formed thereon. Is irradiated with detection light to the scale of the wafer stage WSA from the detection heads 28C to 30D of the frame 54 supported in a stationary state with respect to the projection system PL, and the X direction of the wafer stage WSA and the frame 24, Y Direction relative to the Z direction is detected, the first light beam is irradiated to the reference surface 34 formed on the frame 24 by the AF system, the second light beam is irradiated to the surface of the wafer W1, and the reference surface 34 is used as a reference. As shown, the position (surface position) in the direction along the optical axis of the projection system PL on the surface of the wafer W1 is measured. Here, the formation of the scale on the wafer stage WSA includes, for example, that the scale plates 26E1 and 26E2 on which the scale is formed are fixed to the wafer stage WSA.

According to this embodiment, the surface position (Z position) of the wafer W1 is measured with reference to the reference surface 34 formed on the frame 54 provided with the detection head 28C and the like. Further, the position information of the wafer stage WSA holding the wafer W1 is measured by the encoder method with the detection head 28C and the like provided on the frame 54. Since the measurement is performed based on the frame 54 in common as described above, the wafer with respect to the wafer stage WSA (wafer table 14A) can be used even if the Z position of the frame 54 fluctuates by using the difference between the measurement values of the two. The surface position of W1 can be measured with high accuracy. Therefore, when the wafer W1 is exposed, the influence of the temperature fluctuation of the atmosphere can be reduced, and the position of the wafer stage WSA and the surface position of the wafer W1 can be measured with high accuracy. Therefore, based on the measurement result, the surface of the wafer W1 can be focused on the image plane of the projection system PL with high accuracy.

When an electronic device (microdevice) such as a semiconductor device is manufactured using the exposure apparatus of the above-described embodiment, the electronic device performs step 221 for performing function / performance design of the electronic device as shown in FIG. A step 222 of manufacturing a mask (reticle) based on this design step, a step 223 of manufacturing a substrate which is a base material of the device, a step of exposing the pattern of the reticle onto the substrate by the exposure apparatuses 10 and 10A of the above-described embodiment, Development process of exposed substrate, substrate processing step 224 including heating (curing) and etching process of the developed substrate, device assembly step (including processing processes such as dicing process, bonding process, and packaging process) 225, and inspection It is manufactured through step 226 and the like.

In other words, the device manufacturing method includes exposing a pattern to the substrate using the exposure apparatus (or exposure method) of the above-described embodiment, and processing the substrate on which the pattern is exposed. Yes. At this time, in the exposure apparatus or the exposure method, since the focusing accuracy of the substrate with respect to the projection system PL can be improved, the device can be manufactured with high accuracy. Here, processing the substrate includes developing, heating, etching, dicing, bonding, and the like on the substrate on which the pattern is exposed.
The present invention can be applied to a step-and-repeat type projection exposure apparatus (stepper or the like) in addition to the above-described step-and-scan type exposure apparatus (scanner).

The present invention is not limited to an exposure apparatus for manufacturing a semiconductor device, but is used for manufacturing a display including a liquid crystal display element and a plasma display. Applicable to exposure equipment that transfers device patterns used in ceramics onto ceramic wafers, as well as exposure equipment used to manufacture image sensors (CCDs, etc.), organic EL, micromachines, MEMS (Microelectromechanical Systems), and DNA chips. can do. Further, the present invention is applied not only to a micro device such as a semiconductor element but also to an exposure apparatus that transfers a circuit pattern to a glass substrate or a silicon wafer in order to manufacture a mask used in an optical exposure apparatus and an EUV exposure apparatus. Applicable.

In addition, the illumination optical system and projection optical system of the above embodiment are incorporated in the exposure apparatus main body, optical adjustment is performed, and a reticle stage or wafer stage comprising a large number of mechanical parts is attached to the exposure apparatus main body to connect wiring and piping. Furthermore, the exposure apparatus (projection exposure apparatus) of the above-described embodiment can be manufactured by further comprehensive adjustment (electrical adjustment, operation check, etc.). The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.
It should be noted that the disclosures in the above-mentioned publications, international publication pamphlets, US patents, and US patent application publication specifications described in this application are incorporated herein by reference. In addition, the entire disclosure of Japanese Patent Application No. 2009-139687 filed on June 10, 2009, including the description, claims, abstract, and drawings, is incorporated herein by reference in its entirety. Yes.
In addition, this invention is not limited to the above-mentioned embodiment, A various structure can be taken in the range which does not deviate from the summary of this invention.

R ... reticle, PL ... projection system, W1, W2 ... wafer, WSA, WSB ... wafer stage, ALG ... wafer alignment system, 10, 10A ... exposure apparatus, 18 ... optical system frame, 24 ... scale plate fixing frame, 26A to 26D ... scale plate, 28A, 28B, 30A, 30B ... detection head, 28AZ, 28BZ, 30AZ, 30BZ ... Z head, 34 ... reference plane of AF system, 36 ... AF system unit

Claims

In an exposure apparatus that exposes a pattern on an object via a projection system,
A stage holding the object and moving relative to the projection system;
A frame member which is supported in a stationary state with respect to the projection system and has a diffraction grating-like scale formed so as to face the stage;
A plurality of detection heads disposed on the stage, each of which irradiates the scale with detection light to detect relative position information between the stage and the frame member;
A reference surface formed on the frame member;
Irradiating the reference surface with a first light beam, irradiating the surface of the object with a second light beam, and using the reference surface as a reference, position information of the surface of the object in a direction along the optical axis of the projection system is obtained. A surface position detector for measuring;
An exposure apparatus comprising:
In an exposure apparatus that exposes a pattern on an object via a projection system,
While holding the object and moving relative to the projection system, a stage having a diffraction grating scale formed on the side facing the projection system;
A frame member supported stationary with respect to the projection system;
A plurality of detection heads disposed on the frame member so as to face the stage, and each detecting light on the scale to detect relative position information between the stage and the frame member;
A reference surface formed on the frame member;
Irradiating the reference surface with a first light beam, irradiating the surface of the object with a second light beam, and using the reference surface as a reference, position information in a direction along the optical axis of the projection system on the surface of the object. A surface position detector for measuring;
An exposure apparatus comprising:
3. The exposure apparatus according to claim 1, wherein at least one of the plurality of detection heads detects relative position information of the stage and the frame member in the optical axis direction.
The reference surface side has a long trapezoidal cross-sectional shape, and the reference surface side surface includes a prism member fixed to the reference surface,
A reflecting surface serving as a position reference when the detection head detects relative position information of the stage and the frame member in the optical axis direction is formed on the surface of the prism member facing the reference surface. 4. An exposure apparatus according to claim 3, wherein
The surface position detection device includes a first deflection member that deflects the first light beam toward the reference surface, and a second deflection member that deflects the first light beam reflected by the reference surface,
5. The exposure apparatus according to claim 1, wherein at least one of the first and second deflecting members is supported by the frame member. 6.
6. The exposure apparatus according to claim 1, wherein the reference surface is formed in a recessed portion with respect to the stage of the frame member.
A mark detection system for detecting a mark for alignment of the object;
The stage has a first stage and a second stage that move independently while holding an object to be exposed,
The exposure apparatus according to any one of claims 1 to 6, wherein an optical system of the surface position detection device is disposed between the projection system and the mark detection system.
A reference surface for a mark detection system formed on the frame member;
The mark detection system reference surface is irradiated with a third light beam, the object surface is irradiated with a fourth light beam, and the reference surface is used as a reference along the optical axis of the mark detection system on the surface of the object. A surface detection device for a mark detection system for measuring position information in a direction;
The exposure apparatus according to claim 7, further comprising:
Exposing a pattern on a substrate using the exposure apparatus according to claim 1;
Processing the substrate on which the pattern has been exposed.
In an exposure method for exposing a pattern on an object via a projection system,
Holding the object on a stage that moves relative to the projection system;
A diffraction grating-like scale formed on a frame member supported in a stationary state with respect to the projection system so as to face the stage is irradiated with detection light from the stage, and the stage, the frame member, Detects the relative position information of
A reference surface formed on the frame member is irradiated with a first light beam, a surface of the object is irradiated with a second light beam, and the reference surface is used as a reference along the optical axis of the projection system on the surface of the object. Measure position information in the selected direction,
An exposure method characterized by the above.
In an exposure method for exposing a pattern on an object via a projection system,
Holding the object on a stage that moves relative to the projection system and on which a diffraction grating-like scale is formed;
Irradiating the scale with detection light from a frame member supported in a stationary state with respect to the projection system to detect relative position information between the stage and the frame member;
A reference surface formed on the frame member is irradiated with a first light beam, a surface of the object is irradiated with a second light beam, and the reference surface is used as a reference along the optical axis of the projection system on the surface of the object. Measure position information in the selected direction,
An exposure method characterized by the above.
12. The exposure method according to claim 10, wherein the relative position information includes relative position information of the stage and the frame member in the optical axis direction.
Using a prism member having a long trapezoidal cross-sectional shape on the reference surface side and a back surface fixed to the reference surface,
13. The exposure method according to claim 12, wherein a reflecting surface formed on a surface of the prism member facing the reference surface is used as a position reference of relative position information in the optical axis direction.
The stage has a first stage and a second stage that are independently provided with alignment marks for the object, respectively,
After detecting the alignment mark on one of the first and second stages,
Using the reference plane as a reference, measure positional information in the direction along the optical axis of the surface of the object held by the one stage,
The position of the object in the optical axis direction is controlled when the pattern is exposed to the object on the one stage based on the measurement result. The exposure method according to item.
Exposing a pattern to a substrate using the exposure method according to any one of claims 10 to 14;
Processing the substrate on which the pattern has been exposed.